Internal combustion engines are typically equipped with muffler assemblies for effective noise attenuation during operation. Such a muffler assembly typically includes an outer shell or body with sound-attenuating baffling or the like positioned therein. Exhaust inlet and outlet means are typically provided for routing exhaust gases from the engine in and about the internal baffling. The engines of material handling equipment, automobiles, trucks, as well as other engine-driven devices usually all include one or more muffler assemblies for quiet operation.
One problem which acts to shorten the useful service life of a muffler assembly is the collection or formation of water and like moisture within the muffler body. Moisture collection typically results from condensation of residual exhaust gases within the assembly, or may result from moisture which otherwise enters the muffler body. Moisture within the muffler body frequently results in undesirable corrosion of the metallic material from which the muffler body is formed, and can also flow backwards from the muffler assembly when the engine is not operating and cause corrosion in the exhaust manifold of the engine.
While the provision of a water drainhole at a relatively low portion of a muffler assembly can provide a flow path for draining moisture from the interior thereof, such an expedient is less than satisfactory. Not only does the provision of such a drainhole in a muffler reduce its sound-attenuating capabilities, but further undesirably results in hot exhaust gases and particulate matter carried therein (i.e., soot) being directed against components of a particular device positioned near the drainhole. Such problems can be particularly pronounced in the case of internal combustion diesel engine which can be relatively noisy in operation, and which typically produce exhaust gases having large amounts of particulate matter.
Accordingly, it is very desirable to provide a valve mechanism for a muffler assembly drainhole which permits the flow of moisture and the like from within the muffler assembly when its associated engine is not operating, and which acts to close and seal the drainhole during periods of operation.